This invention relates to an electrical connector and, in particular, relates to an electrical connector having an insulator and a plurality of contacts arranged in line in the width direction of the insulator, wherein the contacts each have a contact portion contactable with a first connection object such as a mating connector and a terminal portion adapted to be fixedly connected to a second connection object such as a printed circuit board.
As this type of electrical connector, there is one in which contact portions of a plurality of contacts are arranged in a plurality of contact portion tiers superposed in the vertical direction (height direction) of an insulator (housing), while, terminal portions of the contacts having the contact portions belonging to (arranged or located in) the respective contact portion tiers are arranged so as to be allocated to one or the other of two terminal portion tiers superposed in the vertical direction of the insulator.
Such an electrical connector is disclosed, for example, in Japanese Unexamined Patent Application Publication (JP-A) No. H7-335343. This publication discloses an electrical connector in which contact portions of a plurality of contacts are arranged in first to fourth contact portion tiers superposed in the vertical direction perpendicular to the width direction of an insulator. In this electrical connector, terminal portions of the contacts having the contact portions belonging to the first contact portion tier and terminal portions of the contacts having the contact portions belonging to the second contact portion tier are arranged in a first terminal portion tier, while, terminal portions of the contacts having the contact portions belonging to the third contact portion tier and terminal portions of the contacts having the contact portions belonging to the fourth contact portion tier are arranged in a second terminal portion tier.
In an electrical connector having an even number of contact portion tiers like the above electrical connector, terminal portions of contacts can be allocated to two terminal portion tiers in a balanced manner.
On the other hand, in an electrical connector having an odd number of contact portion tiers, terminal portions of contacts having contact portions belonging to the middle contact portion tier (e.g. the second contact portion tier when the total number of contact portion tiers is three or the third contact portion tier when the total number of contact portion tiers is five) are allocated to only one of a first terminal portion tier and a second terminal portion tier. Therefore, one of the terminal portion tiers has a greater number of terminal portions than the other terminal portion tier. This difference in number of terminal portions causes a difference in size between occupation spaces of both terminal portion tiers, particularly in the width direction of the electrical connector. Since the occupation space of the entire electrical connector depends on the terminal portion tier having the larger occupation space, it inevitably becomes large in size. This is disadvantageous for miniaturization of the electrical connector.
Further, in an electrical connector of the type adapted to sandwich a plate-shaped second connection object such as a printed circuit board between both terminal portion tiers thereof, the number of terminal portions for connection to one of plate surfaces of the second connection object becomes greater than that of terminal portions for connection to the other plate surface. Therefore, the stability of the electrical connector with respect to the second connection object is poor so that there is a possibility that the electrical connector is inclined in temporary fixing before soldering the terminal portions so as to be offset from the correct position and, after soldering the terminal portions, unwanted stress is applied to the soldered portions.